This invention relates to an electronic device that includes a microprocessor and a display and a structure such that the microprocessor provides output data to the display. More particularly, this invention relates to an electronic device consisting of multiprocessors with a processor unit dedicated to the output refresh requirements of the connected display.
In many electronic devices that include a microprocessor and display function, the algorithm execution and display refresh software have to be intermixed such that the execution of these two functions would be performed in a serial manner. There is a great deal of overhead associated with assuring that the display refresh function is performed in a timely manner within specification. This refresh timing requirement reduces overall software flexibility in that it makes software development more difficult, increases the complexity of software documentation, and degrades the overall efficiency of the software itself. Since in many electronic devices the amount of memory space is limited, this disadvantage can further limit the complexity of the algorithm to be executed.
Interrupt driven microprocessors have been used to execute algorithms and display output data in applications that require a specific refresh timing cycle. In this architecture, the microprocessor will execute the algorithm until the interrupt occurs at which time the microprocessor will execute the display portion of the algorithm in order to refresh the display. This type of software arrangement requires certain overhead to store the location in the algorithm being executed at the time the interrupt occurred and to vector to the interrupt service routine to provide the refresh data. In addition, this architecture requires a programmable timer to provide the interrupt.
The invention disclosed herewith solves many of the above mentioned problems by providing a multiprocessor system that can be implemented on a single semiconductor chip where a single processor unit of the multiprocessor is dedicated to the display function.